| abstract |
WLP semiconductor devices include bump units having a barrier layer for preventing electromigration within the bump units. In one implementation, the bump units include copper pillars formed on the integrated circuit chips of the WLP devices. Barrier layers formed of a metal such as nickel (Ni) are provided on the outer surface of the copper pillars to prevent electromigration in the bump unit. Oxidation prevention caps formed from a metal such as tin (Sn) are provided over the barrier layer. Solder bumps are formed over the oxidation prevention caps. The oxidation prevention caps prevent oxidation of the barrier layer during fabrication of the bump units. |